1. Field of the Invention
The present invention relates to a sensor arrangement for the sensing, through the intermediary of high-frequency means, an actual threat against an object which is equipped with a receiver device by an attacker penetrating into a radio link.
2. Discussion of the Prior Art
A sensor arrangement of the above-mentioned kind is known from the disclosure of German Patent No. 977 984 as an installation for the protection of objects from the effect of missiles. In that arrangement, an object which is either stationary or adapted to travel on land or water carries a transmitter as well as a number of receivers in order, to a certain extent, build up an immaterial or intangible network of radio links in the half space extending about itself. Upon the entry of a foreign body into this network, the radio link which is contacted thereby; acting essentially in the manner of a light barrier, is intended to trigger a defensive medium in the form of a sheaf or burst of the smallest hollow charges in order to damage or even destroy the incoming foreign body. However, inasmuch as this defensive network with its transmitters and receivers for the individual radio links is deployed at a comparatively close distance from the actual object which is to be protected, the object must be armored so as to be protected from the fragmentation effect which is unavoidable during the course of the development of the defensive mechanism. More specifically, any detection of the attacker closely before reaching the object which is to be protected prevents any effective countermeasures, such as evasive maneuvers or the deployment of defensive measures which act at a greater distance. Consequently, this arrangement is not adapted; for example, for the protection of transport aircraft. In addition thereto, there is an increased danger to the object which is to be protected, since for the setting up of the defensive network, it must be equipped with a transmitter and thus can be especially easily located by the attacker.
For a threat analysis extending over a somewhat greater distance, recourse is had to radar installations which operate monostatically, and which can concurrently serve for guidance of air defense missiles, such as in the case of the PATRIOT system; as disclosed in SOLDAT UND TECHNIK, Issue 11/1984, pages 601-609; in particular FIG. 6 on page 606. However, movable objects which are to be protected, and especially protected aircraft, cannot be ordinarily equipped with such voluminous radar installations, quite apart from their heavy power supply for generating a few 100 kVA. Moreover, the inherent endangerment of such radar installations is extremely great due to their high level of energy radiation. However, in the respective position-finding or tracking direction, their effective range is nevertheless comparatively restricted, in view of the emitted energy as well as the energy which is reflected by a potential attacker are presently subjected to an attenuation or dampening effect increasing at square the distance. Finally, such radar installations, in their roundabout surveillance without special directional vectoring, operate relatively sluggishly because they can only search the surroundings in narrow successive directional lobes. This is encountered, because during the roundabout search, the range of detection drops off substantially still more due to shorter dwelling periods of the target within the radar beam.